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NSF/ANSI 14 (plastics piping)

Entry in Sizes, codes and marks · Updated · Written by the Know Your Pipes editors from the sources listed under References

NSF 14, formally NSF/ANSI 14, Plastics Piping System Components and Related Materials, is the NSF standard for plastic pipe, fittings and the materials used to make them[1]. Unlike a health-only standard, it combines health, performance, quality and marking requirements.

One plastic fitting maker summarizes NSF 14 as an assessment of health effects, quality control and assurance, marking, material properties, long-term strength and short-term performance to referenced standards from bodies such as ASTM, ASME and ASSE[2]. Products certified to it carry a designated end use[2].

1 End-use marks

The end-use mark printed on a plastic pipe or fitting says what service it was certified for[2]:

Common NSF/ANSI 14 end-use marks[2]
MarkMeaning
NSF-pwPotable water; meets pressure performance requirements and NSF/ANSI 61 health effects
NSF-dwvDrain, waste and vent; no health effects evaluation
NSF-cwCorrosive waste; no health effects evaluation
NSF-61Health effects only; not evaluated to NSF 14 performance requirements
NSF (end use) SESpecial engineered product with no recognized national performance standard

The difference between pw and dwv is the practical one. A dwv-only mark means the product was not evaluated for drinking water contact, so it is not for supply lines[2]. A special engineered example is an NSF specification for polypropylene DWV fittings that fall outside ASTM D2665, which requires the marking "NSF dwv SE" on each fitting[4]. NSF's own listings sort products by numbered end-use codes, separating potable water uses from non-potable uses such as DWV, sewer and corrosive waste[5].

In practice, a PVC DWV pipe and fitting system made to ASTM D2665 is specified to conform to NSF 14[6], and potable-water pipe such as PVC Schedule 40 pressure pipe is specified to meet NSF 61 plus the health-effects part of NSF 14[7]. See NSF/ANSI/CAN 61 for the health-effects standard and reading pipe markings for the rest of the print line.

2 Code requirements

The 2024 International Residential Code, Section P2609.3, requires plastic pipe, fittings and components to be third-party certified to NSF/ANSI 14[3]. The 2024 Uniform Plumbing Code, Section 301.2.3, requires plastic pipe, fittings and components other than those for gas to comply with NSF/ANSI 14[3]. Section 604.1 of the same code also requires copper-alloy fittings and valves with more than 15% zinc used in plastic piping systems to resist dezincification and stress corrosion cracking in compliance with NSF/ANSI 14[3]; see brass fittings and dezincification.

Adopted codes and local amendments decide what an inspector accepts.

See also

  • Plumbing codes: IPC, UPC and IRCThe three main US model plumbing codes, who writes them, what each covers and how states and cities adopt them.
  • NSF/ANSI/CAN 61The health-effects standard for products that touch drinking water: what NSF 61 tests, what it covers and where codes require it.
  • Reading the print line on pipeWhat the printed or stamped text along PEX, copper and plastic pipe means: size, standards, ratings, listings and date.
  • Nominal pipe size, CTS and IPSWhy pipe sizes are names rather than measurements, and how the CTS and IPS outside-diameter systems differ for the same nominal size.
  • Pipe sizing basics for housesHow water supply pipe sizes for a house are chosen: code minimums, flow, velocity and pressure, and why the job belongs to a plumber.
  • NSF/ANSI/CAN 372 (lead content)The standard used to certify plumbing products to the federal 0.25% lead-free limit, and how to read its marks.

References

  1. NSF, "Product and Service Listings: NSF/ANSI 14 Plastics Piping System Components and Related Materials" — info.nsf.org
  2. Spears Manufacturing, "Appendix C: Product Approvals and Certifications" — spearsmfg.com
  3. Plastics Pipe Institute and Plastic Pipe and Fittings Association, "PEX Plumbing Distribution Systems Design and Installation Guide, Third Edition, Chapter 4: Code Acceptance" (2026) — plasticpipe.org
  4. NSF, "NSF SE 14317: Polypropylene (PP) DWV Fittings" (2014) — info.nsf.org
  5. NSF, "End Use Code Designations" — info.nsf.org
  6. Charlotte Pipe and Foundry, "Submittal: PVC Schedule 40 Solid Wall Pipe and PVC DWV Fitting System" — charlottepipe.com
  7. Charlotte Pipe and Foundry, "Submittal: PVC Schedule 40 Pressure Pipe" (2020) — charlottepipe.com